The primary aim of this study is to evaluate risk factors for preterm birth in a group of low income women. The study will focus on n-3 fatty acids (a certain kind of fat) in diet and in maternal red blood cells, and their association with preterm birth and with other risk factors for preterm birth. The secondary aim relates to intrauterine infection. Bacterial Vaginosis (BV) has long been suspected as a cause of preterm labor. Since administration of n-3 fatty acids as a nutritional supplement has been shown to reduce rates of infection in post-operative patients, we hypothesize that these fatty acids may also play a role in reducing rates of vaginal infections such as Bacterial Vaginosis. We propose to examine this relationship in a population with high rates of BV.